How do we use Gnangara groundwater?
The Gnangara groundwater system is Perth’s lowest cost and largest source of good quality water. The Gnangara groundwater areas consist of three main aquifers – the unconfined Superficial aquifer (commonly known as the Gnangara Mound), the deep, partly confined Leederville aquifer and the deep, mostly confined Yarragadee aquifer.
The Gnangara system provides almost half of all the water used in the Perth metropolitan area each year. It supplies water for agriculture, parks, ovals and gardens on the Gnangara system, and water for Perth’s scheme supply – distributed by the Water Corporation. Gnangara groundwater also supports environmental features such as lakes, wetlands and vegetation.
Gnangara groundwater is Perth’s lowest cost water source and the economic benefits have been estimated at a total net present value of $6.7 billion, which is equivalent to about $400 million a year.
Perth's scheme water
Gnangara groundwater provides at least 110 billion litres or 110 gigalitres (GL) a year for Perth’s scheme water supplied by the Water Corporation (enough water to meet the needs of over 800 000 people).
Horticulturalists and farmers take more than 60 GL of groundwater a year to irrigate locally grown vegetables and fruit.
Parks, gardens and reserves
Local councils, schools and sporting clubs take about 45 GL a year to irrigate parks, sports ovals and other public open spaces.
Local businesses and other commercial industries take over 10 GL a year to irrigate grounds or to use in production of goods and services, such as construction.
Domestic garden bores
We estimate 70 000 individual households take about 36 GL a year through domestic bores to irrigate gardens and livestock (exempt from water licensing). See our main website for more information on how we manage domestic garden bores.
Pine plantations intercept rainfall and reduce or prevent recharge to groundwater.
How much water is used from the Gnangara groundwater system?
Gnangara groundwater supports households, businesses, parks and gardens, through about 2600 water licences to take groundwater and 70 000 domestic bores.
In 2016–17, about 287 GL was allocated from the Gnangara system – enough water to fill Optus Stadium 287 times or 114 800 Olympic swimming pools.
Over 40 per cent of this went into the Water Corporation’s Integrated Water Supply Scheme, and about 45 per cent was used for local parks and grounds, horticulture, and businesses.
About 13 per cent was taken by householders for gardens using domestic bores.